Physical Chemistry Questions

70 For a 1st order reaction A Product the initial concentration of A is 0 1 M and after 40 minute it becomes 0 025 M The rate of the reaction at reactant concentration 0 01 M is A 3 47x10 M min B 3 47x10 M min C 1 735x10 Mmin D 1 735x10 M min

roblem 7 In order to find the strength of a sample of sulphuric acid 10 g were diluted with ter and a piece of marble weighing 7 g placed in it When all action had ceased the marble was removed shed dried and was found to weigh 2 2 g What was the percentage strength of sulphuric acid Solution Mass of macht

7 The standard e m f of a galvanic cell involving cell reaction with n 2 is found to be 0 295 V at 25 C The equilibrium constant of the reaction would be Given F 96500 C mol 1 R 8 314 J K mol 1 2 0 x 1011 ne 2 4 0 x 1012 3 1 0 10 4 1 0 1010

c The enthalpy of hydrogenation of cyclohexene is 119 5 kJ mol 1 If resonance energy of benzene is 150 4 kJ mol its enthalpy of hydrogenation would be a 208 1 kJ mol 1 c 358 5 kJ mol 1 2006 b 269 9 kJ mol 1 d 508 9 kJ mol 1

In order to calculate the ionic product of water accurately the following galvanic cell is used Pt s H g 0 01 atm KOH KCl aq AgCl s Ag s 0 1M 0 01M By measuring cell potential at appropriate concentration the value of ionic product can be calculated Assuming KOH and KCl to be completely dissociated and EC aq AgCl s Ag 0 3 V If E at 320 K is 1 02 V Determine the value of Kw x 10 4 at 320 K cell Give 2 303xRx320 F 0 06

71 For two first order chemical reactions A Products B Products A and B are present initially as A 8 Bo and t 2 of A 10 min t2 of B 20 min If they start reacting at the same time then after how much time in minutes concentration of both would be same

311 On the basis of the following E values the strongest oxidizing agent is Fe CN Fe CN e 1 Fe2 Fe e 1 1 Fe CN 1 3 Fe E 0 35 V E 0 77 V AIPMT Prelims 2008 2 Fe CN 4 Fe

63 Electrode potential data are given below E 0 77 V 57 3 Fe aq e Al 3e Br2 aq 2 aq Fe Al s Al s E 1 66 V MO 2e 2Br aq E 1 66 V Based on the above data which statement s is incorrect 1 Fe2 is stronger reducing agent than Br 2 Fe is stronger oxidising agent than Al 3 Al is stronger reducing agent than Fe2 4 Br is stronger reducing agent than Al 2

Which of the following represents the equivalent conductance at infinite dilution of Al SO Given that A A13 and Aso2 are the equivalent conductances at infinite dilution of the respective ions 2010 a A A13 A 10 so b 2A 3Aso c A Aso 4 34 1 2 6 A 3 A x

7 In which of the given reactions AH AU 1 Combustion of gaseous isopentane at 25 C 2 Hydrogenation of gaseous isobutylene 3 Reduction of ZnO by coke 4 Formation of HI g from H g and 1 g

57 The standard e m f of a galvanic cell involving cell reaction with n 2 is found to be 0 295 V at 25 C The equilibrium constant of the reaction would be Given F 96500 C mol R 8 314 J K 1 mol 1 1 2 0 x 1011 2 4 0 1012 fp

The two equilibria ABA B and AB BAB are simultaneously maintained in a solution with equilibrium constants K and K respectively If A and AB are y and x respectively under equilibrium produced by adding the substance AB to the solvents then K K is equal to A skipped B C v x y x y y x y G

It is given that sigma 1s sigma 2s sigma 2pz are formed by the co axial overlap of 1s 2s and 2pz orbitals of the par ticipating atoms How can more than one orbitals overlap along the same in ter nuclear axis

1 3 77 6 8 8 The value of gas constant R is 8 314 X Here X represents 1 Litre atm K mol 2 Cal mol K 1 3 J K mol 1 4 None of the above 2

Q 35 Consider the following cell 1M ZnSO4 I KNO3 1 M 1 CuSO4 1M II Porous Bone Given volume of solution in each compartment 1 L III Cu 0 76 V Ecu Cr 0 34 Assuming that the current with in cell is carried equally by the positive and nega ions When 0 1 F charge passed What is the concentration of NO in compartment II

The initial rate of hydrolysis of an ester using 1 M HA as catalyst is found to be 0 001 times of the reaction rate by using 1 M HCI In a separate experiment pH of 1 M solution of NaA after hydrolysis is found to be x Report the value of 3x to the nearest integer Assume the reaction is first order w r t catalyst

The correct option s regarding the complex Co en NH3 3 H O En H NCH CH NH is are A B C F It has two geometrical isomers It will have three geometrical isomers if bidentate en is replaced by two cyanide ligands It is paramagnetic It absorbs light at longer wavelength as compared to Co en NH3 4

52 For a reaction with rate equation kC Co dt and C are the concentration at time t 0 and T respectively If 10 min are required for C to Co 2 become the time in minutes required for Co 30 to become 4 is n

Aqueous solution of which of the followin compounds is the best conductor of electri current Re AIPMT 2015 1 Ammonia NH3 2 Fructose C6H 2O6 12 3 Acetic acid C H O 4 2 4 Hydrochloric acid HCI

The energy absorbed by each molecule A2 of a substance is 4 4 10 19 Jand both energy per molecule is 4 0 x 10 19 J The kinetic energy of the molecule per atom will be O2 0 10 20 J 22 10 19 J 020 10 19 J 4 0 10 20 J

8 The equivalent conductance of solution of a 32 weak monobasic acid is 8 0 mhos cm and at infinite dilution is 400 mhos cm The dissociation constant of this acid is AIPMT Prelims 2009 1 1 25 x 10 6 3 1 25 10 4 2 6 25 10 4 4 1 25 10 5

Calculate the maximum kinetic energy of photoelectrons emitted when a light the frequency 2 x 10 6 Hz irradiated on a metal surface with threshold frequency v equal to 8 68 10 5 Hz A 7 5 x 10 18 J C 2 9 x 10 4 J B 4 2 x 10 J D 10 6 x 104 J

Zn s Passage 1 Porous barrier Zn2 NINO Cu2 1M 1M IM Cu t A Galvanic cell consist of three compartment as shown in figure The first compartmer contain ZnSO4 1M and III compartment contain CuSO4 1M The mid compartmen contain NaNO3 1M Each compartment contain 1 L solution 0 76 E Zn2 Cu2 Cu 0 34 concentration of Zn in first compartment after passage of 0 1 F charge will be

9 200 mL of an aqueous solution of a protein contains Its 1 26g The osmotic pressure of this solution at 300 K is found to be 2 57 x 10 3 bar The molar mass of protein will be R 0 083 L bar mol K AIPMT Mains 2011 1 31011 g mol 1 3 51022 g mol 1 2 61038 g mol 1 4 122044 g mol 1

h Molar mass of Cholesterol if 0 00105 mol has a mass of 0 525 g i Mass in grams of 3 102 molecules of Aspirin C H O j Molar mass of an element if mass of 1 atom is 12 10 24 g k Number of SO ions in 19 6 g Cr SO4 3 1 Number of Ca ions in 6 2 g Ca PO Themis

A gaseous mixture of H and He in the mass ratio 1 4 is successively effused through a series of containers connected through narrow tubes of negligible volume and fitted wit valves The valves are successively opened for a very small time interval Find the minimum number of effusion steps required to obtain a molar ratio 8 1 for H and He after the effusion process

A beaker with 155 mL of an acetic acid buffer with a pH of 5 000 is sitting on a benchtop The total molarity of acid and conjugate base in this buffe 0 100 M A student adds 4 10 mL of a 0 310 MHCl solution to the beaker How much will the pH change The pK of acetic acid is 4 740 Express your answer numerically to two decimal places Use a minus sign if the pH has decreased

2 Which of the following solutions does not change its colo on passing ozone through it 1 Starch iodide solution est 2 Alcoholic solution of benzidine 3 Acidic solution of K Cr O 4 Acidified solution of FeSO4

c 30 d 40 4 Find the age of an ancient Egyptian wooden article in years from the given information i Activity of 1 g of carbon obtained from ancient wooden article 7 counts min g ii Activity of 1 g carbon obtained from fresh wooden sample 15 4 counts per min g iii Percentage increase in level of C 4 due to nuclear explosions in past 100 years is 10 iv t 2 of 4C 5770 years m

a 8 16 1 c 16 1 2 b 16 8 1 Tom 9200 d 8 1 2 2014 di to ston 2 g 1 When 22 4 litres of H2 g is mixed with 11 2 litres of Cl2g each at S T P the moles of HCl formed is equal to a 1 mol of HCl g b 2 mol of HCl g c 0 5 mol of HCl d 1 5 mol of HCl g g 2014 12 1 0 g of magnesium is burnt with 0 56 g O in a closed vessel Which reactant is left in excess and how much

A student takes copper aluminium iron and zinc metals separately in four test tubes labelled as I II III and IV respectively He adds 10 mL of freshly prepared ferrous sulphate solution to each test tube and observes the colour of the metal residue in each case He would observe a grey residue in the test tubes 1 II III IV Q a I and II b I and III c II and III I and IV Cu Al Fe Zn the colutions in heaker I II III and IV After

b 8 0 x 102 joules c 4 0 x 10 2 joules d 1 2 x 10 3 joules he work done in joules when 4 5 grams of H202 reacts at 25 C temperature and 1 atmosphere pressure as follows is 2H O 1 O g 2H O 1 b 4 5 10 a 1 63 x 10 c 3 2 x 10 moles of zinc is dissolved in HCI in an open vessel at 25 C Thou d 6 1 10

3 The oxygen in a high pressure cylinder is at 300 K and 100 atm pressure The valve of the cylinder is opened and the gas is allowed to expand to an atmospheric pressure of 1 atm Assuming that the expansion is adiabatic and conducted under condi tions of constant enthalpy estimate the final temper ature of O after expansion Do not assume O to be an ideal gas

2 5 a A piston cylinder arrangement filled with 25 g of ideal gas at 15 C The piston is displace y a distance of 50 mm by applying a mean force of 250 N During the compression process th emperature rises to 25 C Calculate the heat transfer during the process Assume Cy 720 J kg K

X rays of Cuk wavelength 154 pm are diffracted by a set of atomic planes in a crystal in the following manner The separation of the layers in the crystals is 404 pm Find the angle a along which the first order reflection will occur a 79 b 45 V c 11 d None of the above

If and are respectively the wavelengths of the series limit of Lyman and Balmer series of Hydrogen atom then the wavelength of the first line of the Lyman series of the H atom is 1 2 2 2 ydz 3 2 2 2122 2122 4 22 M

500 mL of 0 4 M AgNO3 is mixed with 500 mL of 2 M NH3 solution then the conc of Ag NH3 of solution is represented as 3 3 10 then the value of x is Given Ag NH3 10 K Ag NH3 10

List I I Condensation at normal melting point 1 atm II Fusion at normal boiling point 1 atm III Vaporisation at triple point IV Freezing at normal melting point 1 atm List II P AG 0 Q AG 0 R AS 0 system S AS 0 Which is correctly matched for an endothermic process A I P S T B II P R T C II P R U D III Q R T system T AS system AS U AS system AS surrounding surroun

3 i Write down the generators point groups and the respective group elements to which the following species belong any four

Due to inter electronic repulsion an electron experiences less nuclear charge It is therefore said that inner shell electrons shield the nucleus The actual nuclear charge experienced by an electron is called effective nuclear charge If the electrons in K shell shields the nucleus to the extent of 0 5 say each What will be the wave number of the spectral line arising out of n 4 to n 2 transition in Li atom A C 3 4 RH RH 4 3 B RH 8 D 8RH

5 TEMPERATURE DEPENDENCE OF RATE ACTIVATION ENERGY In gaseous reactions important for understanding the upper atmosphere H O and O react bimolecularly to form two OH radicals AH for this reaction is 72 kJ at 500 K and E 77 kJ mol then calculate E for the bimolecular recombination of 20H radicals to form H O O at 500 K a

f the door of a refrigerator kept in a room is opened the room will a cools down b becomes hot c It is neither hot nor cold d The change in temperature depends on the initial temperature of the room

200 mmHg and 400 mmHg are the vapour pressures of pure liquid components CHCl3 and CH Cl2 respectively which forms an ideal binary solution If 0 75 is the mole fraction of CHCI3 then the total vapour pressure of the solution will be 250 mmHg 200 mmHg 400 mmHg 350 mmHg

The electrical energy n FE produced in a Galvanic cell is a measure of decrease in free energy AG of a cell reaction i e AG nFE For all spontaneous process AG is ve The e m f of the cell reaction 2CeCl aq Zn s 2CeCl3 aq ZnCl aq Varies as E V 0 4108 0 003 T K The AS for the reaction is 1 F 96500 C 579 JK 289 5 JK 1 1158 JK1 868 5JK

Question 43 Assertion Following is a balanced chemical equation for the reaction of magnesium and hot water 2Mg 2H O 2Mg OH 2 H2 Reason The law of conservation of mass holds good for a chemical reaction For the above two statements given one labelled assertion and the other labelled reason Select the correct answer to these questions from the course a b c and d as given below a Both assertion and reason are true and reason is the correct explanation of the assertion b Both assertion and reason are true but reason is not the correct explanation of the assertion c Assert ion is true but reason is false d Assertion is falls but reason is true

75 The dissociation of Nitrogen pentoxide is a first order reaction In first 24 min 75 of N O is dissociated The percentage of NO left behind after one hour of the start of reaction is approximately

ii Construct the matrix for reflection of a point x x z through a plane which contains the Z axis and is at an angle 45 to the X and Y axes 1 5

For a simple cubic crystal X ray diffraction shows intense reflections for angle 0 and 0 wh are assigned to 101 and 1 1 1 planes respectively The ratio sin 8 sin 8 is a 1 5 b 1 22 c 0 82 d 0 67

A gas mixture of volumetric composition 45 CO 50 CO2 and 5 N was passed over ZnO at 1380 K so that Zn vapours was produced according to the reaction ZnO s CO g Zn g CO2 g Under steady condition the rate of input gas flow at STP is 0 224 dm min The rate of loss of mass of ZnO is 5 x 10 4 mol min P 770 torr Find Kp at gas behaviour 1380 K assuming ideal a 0 507 atm c 0 664 atm b 0 0664 atm d 0 325 atm

Analysis for detection of alcohol in blood uses the concept of redox titrations according to reaction unbalanced C H5OH Cr O CO H O Cr 7 In one such experiment 10 ml of 0 05 M K Cr O7 is required to completely neutralise 10 gm sample of blood What is the percentage by weight of alcohol in blood 1 1 15 3 0 115 2 0 0115 4 11 5